Planoobaph co



l. B. JEFFRIES.

AIR TUBE FOR PNEUMATIC TIRES AND PROCESS OF MANUFACTURING THE SAME.

' APPLICATION FILED Aue.24. 1918.

1,309,687. Patented July 15, 1919.

FigzB.

THE COLUMBIA PLANOGHAPM 60-. WASMlNu'mN, D. c.

ITED STATES PATENT OFFICE.

ISAAC BENJAMIN JEFFRIES, OF LLANELLY, WALES.

AIR-TUBE FOR PNEUMATIC TIRES AND PROCESS OF MANUFACTURING THESAME.

Application filed August 24, 1918.

' fixed in the interior thereof, each strip overlapping the adjacent strip and being cut from the loose edge toward the edge which is fixed to the tube, so as to form separate flaps. The strips have been fixed both longitudinally and transversely.

It has been proposed to cement or vulcanize such strips in position. Such strips were out from vulcanized rubber and had square edges and did not fit closely against each other, so that on a puncture taking place, the flap beneath the puncture had to be bent by the outflowing air before it came in contact withthe body of the air tube or with an underlying flap, and as a matter of fact the flap did not always bend snfliciently to make a tight joint and allowed air to escape. It mustbe remembered that such flaps, standing up slightly and not being in contact, would have an equal air pressure on both sides thereof.

According to the present invention I attach the strips of rubber to a foundation by the following method,

The foundation is a sheet of unvulcanized rubber, and the strips are likewise unvulcanized rubber. Each strip is placed in position on the foundation and is pressed or rolled into contact therewith. The strips are cut into flaps, either subsequently to or previonsly to being fixed to the foundation. The strips having all been placed upon the foundation and overlapping each other as usual, the whole is then placed upon a mandrel which is circular in cross section, the strips being in contact with the mandrel. The foundation is bound with canvas, thereby applying pressure to the foundation and strips. This pressure has the effect of squeezing the fixed square edges of the strips into feather or wedge shaped edges, and it further has the effect of squeezing the strips into close contact with and into the body of Specification of Letters Patent.

Patented July 15, 1919.

Serial No. 251,205.

the strips and flaps are formed on the mandrel so as to take up as nearly as possible the precise form required of them, when fulfilling their purpose of effectively sealing a puncture, for when pressed againstthe surface of the air tube by air pressure, each flap has then almost precisely the same position and shape given to it as that obtained by being formed on the mandrel. If a mandrel of ring shape is used as hereafter men tioned, the fit is exceedingly close, because in that case each flap is given not only the proper transverse curvature, but also the correct longitudinal curvature. If a straight cylindrical mandrel is employed this longitudinal curvature is not obtained, Howeveu having regard to the shortness of the flaps, the loss of efliciency by using a straight cylindrical mandrel for large tires, is not substantial enough to affect seriously the utility of my invention.

The foundation with the strips vulcanized thereon as above described, may be attached to an air tube which has been turned inside out, and it may project at one end beyond the tube. The projectin strips, after the tube has been again turned, can easily be inserted into the other end of the tube when the ends of the air tube are being joined. This projecting end overlaps the strips in the other end of the tube, thus leaving no part of the tube unprotected by fia s.

The foundation, instead of being attached to an air tube, may itself form the body of the tube. In this case the mandrel or former is of ring form and I preferably em.- ploy separate portions of foundation with unvulcanized strips attached, which portions are so placed upon the mandrel or former that their edges and the edges of the strips are in contact and are vulcanized together as the strips are being vulcanized to the foundation. By using separate pieces of foundation it obviates the necessity of stretching them to any great extent, which may disarrange the flaps, and theresult is superior to a tube built up with a single piece of foundaend carrying its tion. The foundation may be sufficiently thick to form the body of the air tube or, if too thin for that purpose, it may be covered with a sheet of rubber to produce the desired thickness, the whole being vulcanized The result is that I produce an endless ring covered entirely on the interior with closely fitting flaps, or on that part which will come next to the road surface.

This ring is open on the inner side, as the edges ofthe foundation come down the sides of the mandrel or former but do nottouch each others The air tube is completed by joining the edges in any usual manner.

One advantage of this last described method of producing an air tube is that the interior can be readily examined to ascertain if all the flaps are properly in position before the edges of the foundation are connected to form it into a tube.

Another advantage is that a lighter air tube can be produced, as the foundation itself forms the body of the air tube. 7

Further, this method of manufacture is quicker than'that first above described in which the foundation is fixed. in a tube, especially; if known non-drying material such as glycerin or soft soap be placed in the air tube, as it can e placed inthetube before theedges ofthe foundation are connected, whereas by the first described process it was necessary to turn the tube inside out before applying thenon drying material and then to return the air tube.

If desired a tube madeaccording to the present invention may be provided with male andfemale ends or butt ends of any suitable design. I r

The invention is illustrated in the accompanying drawings, in which Figure 1 is a longitudinal section through a part of the foundation and/strips before vulcanization. V r

Fig. 21s a longitudinal sectionof partof an air tube showing an internal view of the foundation with stripsattached thereto.

Fig. 3 is a longitudinal section through .part'of a ringshaped mandrel or former showing the strips and foundation bound Fig. 4 is atrans'verse section of the mandrel with foundation and strips" thereon, these latter being shown diagrannnatically. Fig. 5 is a longitudinal section of an air tube which is joined by inserting one end ing howthe strips are squeezed'togetherin the vulcanizing process. 7

Fig. 8' is a perspective view of the foundation when "removed from a ring shaped mandrel or former, and Fig. 9 is a side elevation showing the foundation formed into a tube. Fig. 10 is a perspective View of a short length of foundation provided with longitudinal or circumferential strips.

a, a, are the strips of unvulcanized rubber,

which are cemented to the foundation 6 by their edges a, as shown clearly in Fig. 1

This figure also illustrates the. position, which strips of vulcanized rubber assume.

when they are cemented or even vulcanized to a vulcanized foundation. It will be noticed that they are not in close contact and if left so permanently in order to prevent the escape of air through a puncture, they must be deflected by the outgoing flow of air, an effect which is very uncertain to at tain. v V The1str1ps a, a, are cut at M, from their loose edges toward the fixed edges as, in the usual manner. The foundation 6 with its j strips a, is then applied to a mandrel; or

former 0, the strips a being in contact with the mandrel or former. bound tightly around the foundation 6 and Canvas 0! is then" mandrel or former '0, as shownin Figsf3 V and tin like manner to that in'whichfit is bound around an ordinary, air tube in course of manufacture. v Theresult is that the unvuIc aniZed strips a are squeezedinto the shape shown in Figs.

2, '3 and 7, and when vulcanized, perma nently retain that form, havingfeatheror' wedge shaped edges and presenting a per-.

fectly smooth surface with *all the flapsin close contact. When such a foundation is punctured the'fiaps are already in position to closetheaperture or passage and require no deflection whatever.

As shown in Fig. 4' the foundation 7), generally extends on one or both sidesbeyond the strips a. One edge b may be trimmed off, lapped'over the otheredge b and be vulcanized inposition as shown in Fig. 9,

when it is desired to form the foundation?) into an air tube; or both edges maybe trimmed and caused to abut.

.When the foundation and strips are off the man'drelc, they may be carefully examined both inside and out to see that there are no faults in manufacture before the foundation is formed into a tube.

If it is desired to apply a non-drying material such as glycerin or soft soap to the strips 0,, it may also be applied before the edges of the foundation are connected.

If the mandrel c be of ring form, the foundation 7) is endless as shown in Fig. 8 and becomes a finished tube when the inner edges have been connected.

It may, however, be desired to fix a foundation b carrying strips a, within a tube already manufactured. Such a construction is shown in Figs. 5 and 6. The air tube a, c,

- is turned inside out and a foundation 1),

carrying its strips a, is cemented or vulcanized on that part of the tube which is to be toward the road surface. One end of the foundation 2), carrying its strips a, is allowed to loosely project beyond one end 6 of the tube. This loose end is marked Z) in Figs. 5 and 6, and when the ends (a, e of the tube are connected, it overlaps the strips a in the other end 6 of the tube. These last mentioned strips do not need to extend as far as the end a of the tube, as shown in Fig. 5, thus providing room for the entrance of the end 6 of the tube. A certain distance may be left between the end a and the foundation Z) in the end (2, thus insuring that the end a does not disturb the flaps a, a in the other end (a. This unprotected part of the end 6 is, however, proteeted by the overlapping loose projecting part b of the foundation.

I claim 1. A process of manufacturing a pneumatic tube of the character described which consists is cementing unvulcanized strips of rubber to an unvulcanized foundation, cutting the loose edge of the strips toward the fixed edge to produce flaps, placing the strips in contact with a mandrel, and then applying pressure to the exterior foundation and vulcanizing the same.

2. An improved process for manufacturing an air tube as embodied in claim 1 in which the mandrel is of ring formation and the edges of the foundation extend down the sides of the mandrel but are spaced apart, and are subsequently connected.

3. An improved air tube for a pneumatic tire made according to the process claimed in claim 1, in which the strips are vulcanized on to a foundation which is fixed in the interior of an air tube and one end of the foundation is allowed to project from one end of the air tube so that it may overlap the strips in the other end of the air tube when the two ends of the air tubes are connected, substantially as shown and described.

4. An improved process of manufacturing a pneumatic tube as embodied in claim 1 wherein the unvulcanized strips are arranged circun'iferentially of the mandrel and the ends of the strips are vulcanized together.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ISAAC BENJAMIN JEFFRIES.

Witnesses:

DORIS HITCH-1000K, WALTER CARVER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

